Electrodeless high power fluorescent lamp with controlled coil temperature

Abstract

An electrodeless lamp includes a bulbous lamp envelope enclosing an inert gas and a vaporizable metal fill, the lamp envelope having a reentrant cavity, a magnetic core positioned within the reentrant cavity, an induction coil disposed on the magnetic core, a cooling structure disposed inside the magnetic core, and a spacer structure between the magnetic core and an inside wall of the reentrant cavity. The spacer structure defines a thermally insulating gap between the magnetic core and the inside wall of the reentrant cavity to control coil/core temperature.

1 . An electrodeless lamp comprising: 
 a bulbous lamp envelope enclosing an inert gas and a vaporizable metal fill, the lamp envelope having a reentrant cavity;    an electromagnetic coupler positioned within said reentrant cavity; and    a spacer structure disposed between said electromagnetic coupler and an inside wall of said reentrant cavity.    
     
     
         2 . An electrodeless lamp as defined in  claim 1 , wherein said electromagnetic coupler comprises an induction coil positioned within said reentrant cavity and a magnetic core disposed inside said induction coil.  
     
     
         3 . An electrodeless lamp assembly as defined in  claim 2 , wherein said electromagnetic coupler further comprises a cooling structure positioned inside said induction coil and thermally coupled to a lamp base.  
     
     
         4 . An electrodeless lamp as defined in  claim 1 , wherein said reentrant cavity and said electromagnetic coupler have generally cylindrical configurations.  
     
     
         5 . An electrodeless lamp as defined in  claim 1 , wherein said spacer structure is configured to define a gap between the electromagnetic coupler and the inside wall of said reentrant cavity in a range of 1 to 15 millimeters.  
     
     
         6 . An electrodeless lamp as defined in  claim 1 , wherein spacer structure comprises at least one thermally insulating ring disposed between said electromagnetic coupler and the inside wall of said reentrant cavity.  
     
     
         7 . An electrodeless lamp as defined in  claim 1 , wherein said spacer structure comprises two or more spaced-apart thermally insulating rings disposed on said electromagnetic coupler.  
     
     
         8 . An electrodeless lamp as defined in  claim 7 , wherein the spaced-apart rings are joined by struts.  
     
     
         9 . An electrodeless lamp as defined in  claim 7 , wherein a distance between said rings is in a range of 1 to 300 millimeters.  
     
     
         10 . An electrodeless lamp as defined in  claim 1 , wherein at least part of said spacer structure is disposed between an end of said electromagnetic coupler and a closed end of said reentrant cavity.  
     
     
         11 . An electrodeless lamp as defined in  claim 1 , wherein said spacer structure includes at least one spacer that extends beyond an end of said electromagnetic coupler, wherein said electromagnetic coupler is spaced from a closed end of said reentrant cavity.  
     
     
         12 . An electrodeless lamp as defined in  claim 1 , wherein said spacer structure comprises at least one thermally insulating ring having protrusions.  
     
     
         13 . An electrodeless lamp as defined in  claim 1 , wherein said spacer structure is fabricated of a material having low thermal conductivity.  
     
     
         14 . An electrodeless lamp as defined in  claim 1 , which consumes high frequency power in a range of 50 watts to 500 watts.  
     
     
         15 . An electrodeless lamp as defined in  claim 14 , wherein said high frequency power is in a range of 20 kHz to 20 MHz.  
     
     
         16 . An electrodeless lamp as defined in  claim 3 , wherein said cooling structure includes a cooling tube disposed within said induction coil and an extension tube coupled between said cooling tube and a lamp base.  
     
     
         17 . An electrodeless lamp as defined in  claim 1 , wherein said spacer structure comprises two or more spacers disposed on said electromagnetic coupler.  
     
     
         18 . An electrodeless lamp as defined in  claim 17 , wherein said spacers each have an outside diameter that corresponds to an inside diameter of said reentrant cavity.  
     
     
         19 . An electrodeless lamp comprising: 
 a bulbous lamp envelope enclosing an inert gas and a vaporizable metal fill and having a phosphor material on an inside surface thereof, the lamp envelope including a reentrant cavity;    a magnetic core positioned within said reentrant cavity;    an induction coil disposed on said magnetic core;    a cooling structure disposed inside said magnetic core and thermally coupled to a lamp base; and    a spacer structure disposed between said magnetic core and an inside wall of said reentrant cavity.    
     
     
         20 . An electrodeless lamp as defined in  claim 19 , wherein said spacer structure comprises at least one thermally insulating ring disposed between said magnetic core and the inside wall of said reentrant cavity.  
     
     
         21 . An electrodeless lamp as defined in  claim 19 , wherein said spacer structure comprises two or more spaced-apart thermally insulating rings positioned between said magnetic core and the inside wall of said reentrant cavity.  
     
     
         22 . An electrodeless lamp as defined in  claim 21 , wherein the spaced-apart rings are joined by struts.  
     
     
         23 . An electrodeless lamp as defined in  claim 21 , wherein a distance between said rings is in a range of 1 to 300 millimeters.  
     
     
         24 . An electrodeless lamp as defined in  claim 19 , wherein said spacer structure includes a portion positioned between an end of said magnetic core and a closed end of said reentrant cavity.  
     
     
         25 . An electrodeless lamp as defined in  claim 19 , wherein said spacer structure extends beyond an end of said magnetic core.  
     
     
         26 . An electrodeless lamp as defined in  claim 19 , wherein said spacer structure comprises at least one thermally insulating ring having two or more protrusions.  
     
     
         27 . An electrodeless lamp as defined in  claim 19 , wherein said spacer structure is fabricated of a material having low thermal conductivity.  
     
     
         28 . An electrodeless lamp as defined in  claim 19 , wherein said cooling structure includes a cooling tube disposed within said magnetic core and an extension tube coupled between said cooling tube and the lamp base.  
     
     
         29 . An electrodeless lamp as defined in  claim 20 , wherein said at least one thermally insulating ring has an inside diameter that corresponds to an outside diameter of said magnetic core and an outside diameter that corresponds to an inside diameter of said reentrant cavity.  
     
     
         30 . An electrodeless lamp as defined in  claim 19 , wherein said spacer structure comprises an upper spacer and a lower spacer on said magnetic core, wherein said upper spacer extends beyond an end of said magnetic core toward a closed end of said reentrant cavity.  
     
     
         31 . An electrodeless lamp assembly as defined in  claim 19 , wherein the spacer structure defines a gap between the magnetic core and the inside wall of said reentrant cavity in a range of 1 to 15 millimeters.  
     
     
         32 . In an electrodeless lamp including a bulbous lamp envelope having a reentrant cavity and an electromagnetic coupler positioned within the reentrant cavity, a method for enhancing performance comprising: 
 controlling a spacing between the electromagnetic coupler and an inside wall of the reentrant cavity with a thermally insulating spacer structure.    
     
     
         33 . A method as defined in  claim 32 , wherein controlling the spacing comprises spacing the magnetic core and the inside wall of the reentrant cavity by a gap having a dimension in a range of 1 to 15 millimeters.  
     
     
         34 . An electrodeless lamp comprising: 
 a bulbous lamp envelope enclosing an inert gas and a vaporizable metal fill, the lamp envelope having a reentrant cavity;    an electromagnetic coupler positioned within said reentrant cavity; and    means for defining a thermally insulating gap between the electromagnetic coupler and an inside wall of the reentrant cavity.    
     
     
         35 . An electrodeless lamp as defined in  claim 34 , wherein said means for defining a thermally insulating gap comprises means for defining an air gap.